A monolithic current-mode buck converter with advanced control and protection circuits

Feng Fei Ma*, Wei-Zen Chen, Jiin Chuan Wu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

133 Scopus citations

Abstract

A monolithic current-mode pulse width modulation (PWM) step-down dc-dc converter with 96.7% peak efficiency and advanced control and protection circuits is presented in this paper. The high efficiency is achieved by "dynamic partial shutdown strategy" which enhances circuit speed with less power consumption. Automatic PWM and "pulse frequency modulation" switching boosts conversion efficiency during light load operation. The modified current sensing circuit and slope compensation circuit simplify the current-mode control circuit and enhance the response speed. A simple high-speed over-current protection circuit is proposed with the modified current sensing circuit. The new on-chip soft-start circuit prevents the power on inrush current without additional off-chip components. The dc-dc converter has been fabricated with a 0.6 μm CMOS process and measured 1.35 mm2 with the controller measured 0.27 mm2. Experimental results show that the novel on-chip soft-start circuit with longer than 1.5 ms soft-start time suppresses the power-on inrush current. This converter can operate at 1.1 MHz with supply voltage from 2.2 to 6.0 V. Measured power efficiency is 88.5-96.7% for 0.9 to 800 mA output current and over 85.5% for 1000 mA output current.

Original languageEnglish
Pages (from-to)1836-1846
Number of pages11
JournalIEEE Transactions on Power Electronics
Volume22
Issue number5
DOIs
StatePublished - 1 Sep 2007

Keywords

  • Compensation ramp
  • Current sensing
  • Current- mode control
  • Over-current protection
  • Power management
  • Pulse frequency modulation (PFM)
  • Pulse width modulation (PWM)
  • Soft-start
  • Switching dc-dc converter

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